Investigation of etch characteristics of non-polar GaN by wet chemical etching

Hsu, Hsiao-Man; Su, Yan–Kuin; Cheng, Shin-Hao; Huang, Shyh-Jer; Cao, Jiaming; Chen, Kuan-Chun

doi:10.1016/j.apsusc.2010.08.017

Cited by 15 publications

(7 citation statements)

References 20 publications

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“…Alternatively, the surface can be etched (via heated KOH [13][14][15] or phosphoric/sulfuric 14,16 acid) or coated with thiols, 17 or other molecules. [18][19][20][21][22][23] The etching and surface functionalization routes provide convenient ways to modify GaN surface properties without the need for intensive doping strategies that predominantly rely on hazardous chemicals.…”

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confidence: 99%

Effect of etching with cysteamine assisted phosphoric acid on gallium nitride surface oxide formation

Wilkins

Paskova

Ivanisevic

2013

Journal of Applied Physics

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In-situ functionalization of polar GaN was performed by adding cysteamine to a phosphoric acid etchant in order to study its effect on photoluminescence and oxide formation on the surfaces. The functionalization was characterized by atomic force microscopy, x-ray photoelectron spectroscopy, photoluminescence (PL), and water contact angle measurements. Two sets of polar GaN samples with different dislocation densities were evaluated, thin GaN layers residing on sapphire and thick free-standing GaN separated from sapphire substrate aiming to reveal the effect of material quality on in-situ functionalization. The addition of cysteamine to the phosphoric acid solution was found to result in: (i) decreased surface roughness, (ii) no change to hydrophobicity, (iii) decreased oxygen content especially at high-temperature treatments. The effect of the in-situ functionalization on the PL efficiency was more pronounced in the free-standing sample than in the film residing on the sapphire, which was attributed to a higher crystal quality free from strain.

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confidence: 99%

Effect of etching with cysteamine assisted phosphoric acid on gallium nitride surface oxide formation

Wilkins

Paskova

Ivanisevic

2013

Journal of Applied Physics

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“…As evaluation spots were selected randomly across the sample, it is likely that images may show unusual smooth regions. It should be noted that the v-grooves and pits did not increase in length as treatments were relatively mild (not long enough or hot enough) to promote preferential etching as seen elsewhere. ,, The thin heteroepitaxial nonpolar GaN layer demonstrated a greatest surface roughness due to a higher density of stacking faults and associated partial dislocations that is common with this growth technique …”

Section: Resultsmentioning

confidence: 67%

“…The nonpolar bulk GaN displays a smooth surface relative to that of thin-layer heteroepitaxial GaN, which is characterized by pits. Unlike the free-standing bulk polar GaN, the nonpolar GaN surface of the thin layer is characterized by deep diamond shaped pits and v-grooves, which are characteristic of stacking faults manifesting themselves through partial dislocations along polar directions. ,, These grooves are essentially a side view of uniformly shaped polygonal pits seen from the polar GaN . No correlation is discernible between etchant temperatures or composition, as treatments resulted in relatively smooth surfaces.…”

Section: Resultsmentioning

confidence: 99%

“…It should be noted that the v-grooves and pits did not increase in length as treatments were relatively mild (not long enough or hot enough) to promote preferential etching as seen elsewhere. 19,28,31 The thin heteroepitaxial nonpolar GaN layer demonstrated a greatest surface roughness due to a higher density of stacking faults and associated partial dislocations that is common with this growth technique. 24 Due to the large standard deviation across the sample sets, no clear correlation can be made regarding the effect of the phosphonic acid attachment on the surface roughness.…”

Section: ■ Experimental Methodsmentioning

confidence: 99%

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In Situ Chemical Functionalization of Gallium Nitride with Phosphonic Acid Derivatives during Etching

et al. 2014

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In situ functionalization of polar (c plane) and nonpolar (a plane) gallium nitride (GaN) was performed by adding (3-bromopropyl) phosphonic acid or propyl phosphonic acid to a phosphoric acid etch. The target was to modulate the emission properties and oxide formation of GaN, which was explored through surface characterization with atomic force microscopy, X-ray photoelectron spectroscopy, photoluminescence (PL), inductively coupled plasma-mass spectrometry, and water contact angle. The use of (3-bromopropyl) phosphonic acid and propyl phosphonic acid in phosphoric acid demonstrated lower amounts of gallium oxide formation and greater hydrophobicity for both sample sets, while also improving PL emission of polar GaN samples. In addition to crystal orientation, growth-related factors such as defect density in bulk GaN versus thin GaN films residing on sapphire substrates were investigated as well as their responses to in situ functionalization. Thin nonpolar GaN layers were the most sensitive to etching treatments due in part to higher defect densities (stacking faults and threading dislocations), which accounts for large surface depressions. High-quality GaN (both free-standing bulk polar and bulk nonpolar) demonstrated increased sensitivity to oxide formation. Room-temperature PL stands out as an excellent technique to identify nonradiative recombination as observed in the spectra of heteroepitaxially grown GaN samples. The chemical methods applied to tune optical and physical properties of GaN provide a quantitative framework for future novel chemical and biochemical sensor development.

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“…This cross-section morphology was caused by the chemical activity difference between Ga-polar and N-polar GaN. In the previous research, the difference of the chemical property between Ga-polar and N-polar GaN surface was reported 27 . N-polar GaN surface was etched in H 3 PO 4 at 90 °C in some reports 28 .…”

Section: Resultsmentioning

confidence: 90%

High quality self-separated GaN crystal grown on a novel nanoporous template by HVPE

Huo

Shao

et al. 2018

Sci Rep

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In this study, a novel nanoporous template was obtained by a two-step etching process from MOCVD-GaN/Al2O3 (MGA) with electrochemical etching sequentially followed by chemical wet etching. The twice-etched MOCVD-GaN/Al2O3 (TEMGA) templates were utilized to grow GaN crystals by hydride vapor phase epitaxy (HVPE) method. The GaN crystals were separated spontaneously from the TEMGA template with the assistance of voids formed by the etched nanopores. Several techniques were utilized to characterize the quality of the free-standing GaN crystals obtained from the TEMGA template. Results showed that the quality of the as-obtained GaN crystals was improved obviously compared with those grown on the MGA. This convenient technique can be applied to grow high-quality free-standing GaN crystals.

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Investigation of etch characteristics of non-polar GaN by wet chemical etching

Cited by 15 publications

References 20 publications

Effect of etching with cysteamine assisted phosphoric acid on gallium nitride surface oxide formation

Effect of etching with cysteamine assisted phosphoric acid on gallium nitride surface oxide formation

In Situ Chemical Functionalization of Gallium Nitride with Phosphonic Acid Derivatives during Etching

High quality self-separated GaN crystal grown on a novel nanoporous template by HVPE

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